Fault Tree Modeling for AAC DG Sharing in Multi-unit Loss of Off-Site Power Accidents

Abstract

Since the existing probabilistic risk assessment (PRA) considers an accident that occurs only in one unit, it is assumed that equipment shared by two adjacent units is always available. However, if a simultaneous accident occurs in two units and operation of the shared equipment is required at the same time, only one of the units is available and therefore, use in the other unit may become unavailable. Therefore, in this study to consider this unavailable state, we would like to present a fault tree modeling applying the IF-THEN rule that can calculate the failure probability of the operation of alternate AC diesel generator (AAC DG), a representative shared equipment, in various accident sequences that may occur in a multi-unit loss of off-site power (MULOOP) accident.